Consolidated Statements of Changes in Stockholders’ Equity (Unaudited) (USD $) In Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member] Outstanding Common Shares Repurchased [Member]	Treasury Stock [Member] Shares Repurchased To Fund Options Exercised [Member]	Treasury Stock [Member] Shares Repurchased To Satisfy Tax Obligations [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance, beginning of period at Dec. 31, 2011	$ 315	$ 195,628				$ (7,355)	$ 223,510	$ 4,813
Repurchase of outstanding shares			(1,721)	(548)	(502)
Change in net unrealized gains (losses) on securities available for sale, net of taxes of approximately $14,140 and ($2,566) for the six months ended June 30, 2013 and 2012, respectively								3,269	3,269
Amortization of actuarial losses, net of taxes of approximately ($270) and ($233) for the six months ended June 30, 2013 and 2012, respectively								298	(298)
Amortization of prior service credits, net of taxes of approximately $10 for both six month periods ended June 30, 2013 and 2012)								(13)	13
OTTI charges included in income, net of taxes of approximately ($220) and ($339) for the six months ended June 30, 2013 and 2012, respectively)								437
Net income							15,766		15,766
Cash dividends declared and paid on common shares ($0.26 per common share for the six months ended June 30, 2013 and 2012, respectively)							(7,931)
Award of common shares released from Employee Benefit Trust (137,346 and 150,564 common shares for the six months ended June 30, 2013 and 2012, respectively)		1,398
Shares issued upon vesting of restricted stock unit awards		317				1,684	(98)
Issuance upon exercise of stock options		97				1,356	(23)		548
Stock-based compensation activity, net		191
Stock-based income tax benefit		78
Balance, end of period at Jun. 30, 2012	315	197,709			(7,086)		231,224	8,804	430,966
Balance, beginning of period at Dec. 31, 2012	315	198,314				(10,257)	241,856	12,137	442,365
Repurchase of outstanding shares			(12,609)	(1,750)	(754)
Change in net unrealized gains (losses) on securities available for sale, net of taxes of approximately $14,140 and ($2,566) for the six months ended June 30, 2013 and 2012, respectively								(18,218)	(19,837)
Amortization of actuarial losses, net of taxes of approximately ($270) and ($233) for the six months ended June 30, 2013 and 2012, respectively								348	(348)
Amortization of prior service credits, net of taxes of approximately $10 for both six month periods ended June 30, 2013 and 2012)								(12)	12
OTTI charges included in income, net of taxes of approximately ($220) and ($339) for the six months ended June 30, 2013 and 2012, respectively)								283
Reclassification adjustment for gains included in net income, net of tax of approximately $1,257 for the six months ended June 30, 2013								(1,619)	(1,619)
Net income							16,383		16,383
Cash dividends declared and paid on common shares ($0.26 per common share for the six months ended June 30, 2013 and 2012, respectively)							(7,879)
Award of common shares released from Employee Benefit Trust (137,346 and 150,564 common shares for the six months ended June 30, 2013 and 2012, respectively)		1,556
Shares issued upon vesting of restricted stock unit awards		160				2,335	(99)
Issuance upon exercise of stock options		116				2,056	(69)		1,574
Stock-based compensation activity, net		(192)
Stock-based income tax benefit		324
Balance, end of period at Jun. 30, 2013	$ 315	$ 200,278			$ (20,979)		$ 250,192	$ (7,081)	$ 422,725